Evidence of a female-produced sex pheromone in the European pear psylla, Cacopsylla pyri

Cacopsylla pyri (L.) (Hemiptera Psyllidae) is one of the most important pests of pear orchards in Europe that reduces the market value of pears. Summerform C. pyri males significantly preferred odours from living females or female cuticular extracts in the absence of visual stimuli in a Y-tube olfactometer. Conversely, males as well as females did not show any preference for odours from specimen of the same sex. Electroantennogram recordings showed that female cuticular extracts elicit dose-dependent responses in male antennae suggesting the presence of volatile compounds capable to stimulate the male peripheral olfactory system. Gas-chromatography coupled with mass spectrometry revealed marked quantitative differences between male and female cuticular extracts regarding 13-methylheptacosane, 11,13-dimethylheptacosane, 2-methylheptacosane, and 3-methylheptacosane. These compounds were found in larger amounts in female extracts which suggests their role in male attraction

Evidence of a female-produced sex pheromone in the European pear psylla, Cacopsylla pyri

Cacopsylla pyri (L.) (Hemiptera Psyllidae) is one of the most important pests of pear orchards in Europe that reduces the market value of pears. Summerform C. pyri males significantly preferred odours from living females or female cuticular extracts in the absence of visual stimuli in a Y-tube olfactometer. Conversely, males as well as females did not show any preference for odours from specimen of the same sex. Electroantennogram recordings showed that female cuticular extracts elicit dose-dependent responses in male antennae suggesting the presence of volatile compounds capable to stimulate the male peripheral olfactory system. Gas-chromatography coupled with mass spectrometry revealed marked quantitative differences between male and female cuticular extracts regarding 13-methylheptacosane, 11,13-dimethylheptacosane, 2-methylheptacosane, and 3-methylheptacosane. These compounds were found in larger amounts in female extracts which suggests their role in male attraction

Behavioural and electrophysiological responses to overlooked female pheromone components in the olive fruit fly, Bactrocera oleae (Diptera: Tephritidae)

The olive fruit fly, Bactrocera oleae, has a peculiar sexual chemoecology, guided by both male- and female-borne olfactory cues, mostly produced in rectal glands. Despite the research on B. oleae female pheromones has a long history, only few components (mainly 1,7-dioxaspiro[5.5]undecane) have been deeply investigated. Detailed evidences about the chemical identity and bioactivity of several others C10–C18 molecules produced in female rectal glands are lacking. We conducted GC and GC/EI–MS, identifying nine sex-specific chemicals and an additional compound [ethyl(Z)-9-octadecenoate], less abundant in females over males. Age-related production of all compounds raised over time. In 21-day-old females, it reached amounts from a minimum of 8.08 ng/fly (n-butyl dodecanoate) to a maximum of 87.19 ng/fly (ethyl hexadecanoate). In EAG experiments, all chemicals were perceived by both sexes. Methyl hexadecanoate and ethyl decanoate attracted males and females, respectively. This is the first report on a female-borne compound attracting conspecific females in Tephritidae. Our study sheds light on the bioactivity of female-borne pheromones involved in the B. oleae chemoecology. Further research is ongoing to test methyl hexadecanoate and ethyl decanoate as lures to enhance sex pheromone blends used in IPM programmes against B. oleae, thus improving control tools against this key pest

Attraction of Sitophilus oryzae (L.) (Coleoptera: Curculionidae) to the semiochemical volatiles of stored rice materials

In order to explore the influence of stored cereal volatiles on the behavior of Sitophilus oryzae, the olfactory responses of adult rice weevils to the volatiles of different rice cultivars [Red brown rice (RBR), Daohuaxiangmi (DHXM), Baishuigongmi (BSGM), Yashuixinmi (YSXM), and white glutinous rice (WGR)] were studied using electroantennography (EAG) and behavioural bioassays in different types of olfactometers. S. oryzae showed significantly different preferences for these rice cultivars, in the order RBR > DHXM = YSXM >= BSGM > WGR. Furthermore, 26 components were identified in the volatile profile of RBR. Nonanal (29.37%), hexanal (16.08%), and 1-octen-3-ol (8.83%) were the most abundant compounds. EAG recordings showed that the antennae of S. oryzae were able to perceive these three compounds in a dose-dependent manner. The compounds elicited significant EAG responses at various concentrations, with the strongest responses at 100 mu g mu L-1. S. oryzae had a significant positive behavioural response to nonanal, hexanal, and 1-octen-3-ol at various concentrations, with the most attractive being 50, 100, and 100 mu g mu L-1, respectively. The olfactory preferences of S. oryzae, based on a comparison of these compounds at their optimal concentrations, were nonanal > 1-octen-3-ol = hexanal. These results indicated that the volatiles of the preferred rice cultivar (RBR) were perceived by the peripheral olfactory system of S. oryzae adults and individually elicited positive chemotaxis. These findings offer new insights into the mechanism of host preferences of stored-grain pests. Nonanal showed the greatest potential for use as a novel monitoring and control tool against this storage-beetle pest